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  1. Calcite
  2. CALCITE-5155

Extensible time units

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    • Bug
    • Status: Open
    • Major
    • Resolution: Unresolved
    • None
    • None
    • None
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    Description

      Allow a type system to define its own time units and how they are rolled up.

      Currently, time units are used in the EXTRACT, FLOOR, TRUNC functions, and include YEAR, QUARTER, MONTH, HOUR, MINUTE, NANOSECOND. For example FLOOR(t TO HOUR) is valid.

      A type system would be allowed to define extra time units. Once a time unit is defined the EXTRACT, FLOOR and TRUNC functions should just work.

      The definition of might consist of a base unit and multiplier. So MINUTE15 would be based on MINUTE with a multiplier of 15. 

      Various rules know that you can roll up FLOOR(t TO DAY) to FLOOR(t TO MONTH) but you cannot roll FLOOR(t TO WEEK) to FLOOR(t TO MONTH). When you define a new time unit, the type system can deduce that full set of time units that it can roll up to, and which can roll up to it.

      Should we support time units that do not evenly divide the next largest time unit? For example the number of seconds since the top of the hour modulo 7. 60 and 3,600 are not a multiples of 7, so SecondOfHourMod7 would be different from SecondOfMinuteMod7.

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              Unassigned Unassigned
              julianhyde Julian Hyde
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                Created:
                Updated: